Lifting mechanism



July 19, 1949. R. F. MANKE.

' LIFTING MECHANISM 4 Sheets-Sheet 1 Filed Sept. 17, 1943 INVEN TOR.

July 19, 1949. v I R. F. MANKE I 2,476,380

LIFTING MECHANISM Filed Sept. 17, 1943 4 Sheets-Sheet 2 INVEN TOR.JZdgzr/a/Y/ F/fc.

July 19; 1949. R. F. MANKE 5,

LIFTING MECHANISM 4 Sheets-Sheet 3 Filed Sept. 1'7, 1943 July 19, 1949.R. FQMANKE 2,476,380

LIFTING MECHANISM Filed Sept. 1'7, 1945 4 Sheets-Sheet 4 Patented July19, 1949 l LIFTING MECHANISM RaymondiF.

Manke, Racine, Wis, assignor to.

W alkcr Manufacturing Company of Wisconsin,

Racine, Wis., a corpora tion of Wisconsin 7 Application September 17,1943, Serial No. 502,780

4Claims. (Cl. 254-23 V The present invention relates to liftingmechanisms, and in the herein disclosed embodiments, provides improvedlifting mechanisms for use in plprtable jack structures, industrialtrucks and the l (e. l

The principal objects of the present invention are to provide liftingmechanisms, which may be readily and economically manufactured andassembled and which are reliable and efficient in operation; to providesuch structures embodying improved arrangements of lifting elements,which can be collapsed into a relatively small space, thereby minimizingthe necessary height and length of the structure; to provide such astructure wherein a substantially vertical lift may be imparted-to aload engaging element by means of a power applying member which moves ina generally horizontal path; to'provide such structures embodying alifting arm, which carries a load engaging element and which is bothswung and moved bodilyv so that the load engaging'element moves in asubstantially -linear vertical path; to provide such structuresincluding supplemental lifting elements, herein illustrated ascomprising inclined planes, which function during and facilitate theinitial lifting movement; to provide such structures incorporating animproved arrangement of supporting wheels, which facilitates the use ofthelstructure on irregular surfaces; and to provide an improved andsimplified construction and arrangement of lifting mechanisms. J f aWith the above aswelljas' other and more detailed objects in view, whichappearin the following description andinfithe appended claims, preferredbut illustrative embodiments of the invention are shown in theaccompanying drawings, throughout the several views of whichcorresponding reference characters are used/to designate correspondingparts and in which:

Figure 1 is a view in side elevation, with certain of the parts brokenaway, of a portable floor jack embodying the invention;

Fig. 2 is a plan View, with certain of the parts broken away, of thestructure of Fig. 1; Fig. 3 is a view corresponding generallyto Fig. 1,but showing the structure inthe fully and partially elevated positions;Fig. 4 is a view in vertical section, taken along the 'line 4-4 of Fig.13; V

Fig. 5 is a fragmentary viewin vertical section, takenalong the line 5-5of Fig. 2;

Fig. 6 is a fragmentary viewof a bodiment of the inventiqm;

further em- Figs. *7 and 8, are YlEWSg respectively, in side shields 48and 50,

elevation withcertain of the parts broken away, and in horizontalsection, of'a further embodiment of the invention; and f g Figs. 9 and10 are,respectively, views in side elevation and in plan,'with certainof the parts broken away, of an embodiment of the invention which,corresponds generally to the embodiment of Figs. 1 through "5, with theexception that a different powerapplying mechanism is used.

It will be'appreciated standing of the preslentihvention that theimprovements thereof may be embodied in lifting structures intended forwidely differingus'es, and incorporating widely differing structuralarrangements. Preferred applications of the invention are in connectionwith floor jacks, industrial trucks and the-like, and in an illustrativebut not in a limiting sense, the invention is so disclosed herein. A

Referring firstto Figs. 1 through 5, the illustrated portable floor jackcomprises generally a frame structure 20, which is supported by a seriesof four wheels 22; a lifting cap 24, which is carried at the forward endof a lifting arm 26, for movement between the retracted position shownin Figs. 1 and 2, and the fully elevated position shown in Fig. 3; and apower applying element 28, herein illustrated as aconventionalghydraulic ram and pump unit, which responds to rockingmovements of a usual-handle structure, 39;."

The frame 20 is constituted by a pair of longitudinally extending,laterally spaced, similar, but oppositely presenting members All and 42,which, as best appears in Fig. 4, are of channel-shaped form throughoutthe ,major portions of their length. Adjacent their fronten'ds, themembers 46 and 42 are formed to define hoods 4t and 66, within which thefront wheels 22 are conventionally received. Adjacent their rear ends,the members 40. and 42 are provided with similar which, respectively,receive the rear wheels 22. As will be understood, the rear wheels 22may, if desired, be carried by swivel arms. The members 40 and 42 maybemaintained in rigid unitary relation to each other in any suitable way.As shown, this is accomplished by front and rear stay bolts 52and and bythe base 56 (Figl 4) of .the hereinafter described fixedplane 58..Thebase. 55 is secured to the respective members M and, 42 by corresponding pairs of studsiGlL, c .1

The lifting arm 25..sco1'1stituted bya. p-airof laterally spaced legs'lflQand 312,1 which are connected together, thr dllghmlt a portionv oftheir length, by we ge: 'Tliel'front ends of the legs from a completeunder- I 70 and 12 are pivotally connected, by a pin 78, to a capadapter 18, to which the cap 24 is rotatably secured. The rear ends ofthe respective legs i8 and 12 are provided with rollers 80, one of whichis shown in Fig. 2. Each roller 80 is rotatably journalled upon a pin82, and is supported in place thereon between the enlarged head of thepin and the outerjfaceof the corresponding arm I or I2. Each'pin 82 isprovided with a reduced inner end, which passes through thecorresponding arm or 12, and also, through a reinforcing plate 84,carried at the inner side of 'such'arrn. As will be understood, inassembly the .pin is passed through the arm and reinforcing plate, afterwhich the inner end of the'pi-n is radially enlarged to retain the partsin assembled relation.

The respective rollers 80ride in grooves or guideways 90 individualthereto, one of which is shown in Fig. 5, as comprising upper and lowerportionswhich are integralwith and project inwardly from the w'eb ofjtheside frame member 42. The guide'or runway for the roller associated witharm 10 is similarly arranged, as will be un= derstood; As alsoappear'sin'l ig. l, the front and rear ends of the'runways. 90 are closed, sothat these runways may beiutilized to limit the extent of movement ofthe'reflar endof the lifting arm 26.

The liftingjforceisapplied to the lifting arm 26by.meansl'oflaterallyspaced, radius or stabilizer arms I00 and;I;02'.The lower ends of arms I00 and' I02arejpivotallyconnected to the frameby means .of the prev'iously mentioned front tie rod 52, whichr nay, ifdesired, be provided with spacing sleeves or;other means to maintain thearms I00 and I02jinproper position lengthwise of the tie rod; Theupperendsof the arms I03 and I02 are pivotally, connectedtothe correspondinglegs"10"and12' of the lifting arm 26, by means of pins I04. and I06. Thepin I06 is shown in detail inFig Z and pin. I04 is similarly associatedwith legln anda'rmi I00.

In order to stabilize the 02.1324 and maintain its upper surface in" .asubstantially horizontal position thro ughout"the travel of the liftingarm 26, a pair of similar; laterally spaced stabilizing arms' I I0 andH2, are 'pivot'ally connected at their outer ends tothe ca'p'adapted I8,as by pin IM, and are pivotally' connected at their inner ends to thecorresponding radius'arms I00 and H12, by pins IIGand II'8. It will" beappreciated that the pivotal connectionsgof the'lifting arm 26 and thes'tabilizingarms I'I Band I I2 to the cap adapter I8 andtotheradius'arms I00 and I02 are so located, relative to the paths-ofmovement of the lifting arm and-the'ra'dius as to maintain the cap 24 ina substantially horizontal position throughout its travel. a

The lifting force i's appliedto the radius arms I00 and I02 by meanseithe head I20, which operatively engagesa roller I22. Roller I22 isrotatably supported upon the pin I24, which is secured to and extendsbetween the radiusarms I00 and" I02. The head I isrigidly secured at theouter end of theram' I which, in the embodiment now' being described,constitutes the piston rod of the previously mentioned hydraulic ram andpump unit 28'. v I

The unit 28 may be and preferably is conventionally constructed'and,consequently, does not require detailed description, It is noted,however, that this unit comprises rigidly interconnected cylinder andvpump portions I32 and I34. As shown, the pump structure embodies bothspeed and power elementsgvvhichgin turn, are provided with. rearwardlyprojecting piston portions lat 7 structure to be kept a 4 and I38, whichare pivotally'couple'd to operating links I40 and I42. The operatinglinks I40 and I42, in turn, are pivotally connected to an operatingsegment I50. Segment I50 is pivotally supported between the side framemembers 40 and 42 by means of a pin I52. The pin I 52 also serves topivotally support the previously, mentioned operating handle 30, which;in accordance with usual practice, is releasabli c'on'ne'ctib'l'e to thesegment I50 in any of a plurality of relative rotative positions of thesegment and handle, thereby enabling-adjustment of the arcuate path oftravel of the handle. addition to the releasable latch: I54, whichcontrols' the last-mentioned connec tion. the handle 30 may be andpreferably is provided with a valvebontrolling element I 5%, which;

may be operatedtozpermit a return or retracting movement of the ram unit28.

of the unit 28 with outwardly projecting trunnion's- .157, which arereceived; in corres'poriding sockets E59 provided'in the sid'franie"embers IEVand' 32. As thus far desc b '7 that the parts no U V occ pthepositions shown in Figs. l andf i "'ch' he lifting arms, the radiusarms andtl're stab "zen armsiare' collapsed within the"confines'nf theframe-members so and 42, and in wh cn t f position substantially lev lwith'itheupp-er surface of the frame. ilnden these 'condit n s, t hecol.lapsedlifting armyrad ius 'arms rid 'biiizrarms 7' i pg sition's;eightof the jack v ery'lowvalue; As thus far described, also, it willbeapblie'ciated"that a rightward movement of the 'head I20? influv .i 5out the pin 5211s a; clock h the pins I04a'nd' I00; this movement. of:the j-r'a s 'arms'ffis communicated to the liftingarm zffi nd 'cause'"'the latter to swing in a counterclockwise dire 1on1 Since the aXis ofthe n 1 i and I1 6 m ves; to t e wise direction. 'Ifhrouh vertical path;n H from this latter feature will beapparent; it being recognized thatwithconyentional cantilever-typejack structures-,the lifting movementinvolves either a shift in'thejposition 'ofth'e loa'd; or ashift 1 inthe position of the' jack'r.

Coming" now 'to' a description ofthe supplemental lifting elementscomprising-thefixed; in"- clined plane 58 and"the cooperating, inovable,

inclined plane error-ace 'by'th head rzni i ill be appreciated that w'"ft" In the present.

embodiment, the ram and pump unit partakes of;

e appreciated" inging of the arms H.30-

26' to cause leftward" -res ultant'cap.riiov-. ment is, consequentl' y asubstantially" linear any'a vantages r sumes elements and the ram I30lie substantially parallel to each other, so that a given rightwardforce exerted by the ram I30 against the lifting elements has only arelatively small vertical component of force. It is the purpose of thesupplemental lifting elements to elevate the previously describedlifting elements to such a height that the angle between the ram and theradius arms is sufficient to enable the ram unit to complete theelevating movement without the expenditure of an undue amount of force.

-lVIore particularly, the previously mentioned fixed, inclined plane 58is provided with an inclined surface I60, which may either be formedintegrally therewith or may be separately formed and thereafter fixed inplace thereon. The surface I60 affords a supporting runway for a rollerI62, which is supported between the bifurcated legs I64 on the head I20,by means of a pin I66.

The head I20 is provided along its forward face with an inclined surfaceI10, having curved or socket portion I12 at its upper end. The surfaceI10 is coextensive in width with the head I20 from the socket I12 downto the point a, in Fig. 1. From the point a to the point b in Fig. 1,the surface I10 is constituted by the upper surfaces of the previouslymentioned legs I64.

In the normal or retracted position of the structure, the parts occupythe positions shown in Fig. 1, in which the roller I62 is seated uponthe extreme lower and slightly curved end of the inclined surface I60,and in which the roller I22 is seated upon the extreme lower end of theinclined plane surface I10. The parts are normally retained in thesepositions, as will be understood, by a usual tension spring I80, whichis connected between the head I20 and the cylinder portion of the ramand pump unit 28. A rightward move ment of the head I20, as influencedby the ram and pump unit 28, causes the roller I62 to ride upwardlyalong the inclined surface I60, which movement has a substantialvertical component. The rightward movement of the head I20 also causesthe inclined surface I10 to move to the right relative to the pin I22,and cam the latter upwardly. The vertical movement of the pin I22 is, ofcourse, directly transmitted to the radius arms I and I02 and,consequently, to the lifting arm 26, it being noted that the netvertical movement of the pin I22 is equal to the sum of the verticalmovements of the head I20 and the vertical movement of the pin I22relative to the head I20.

As indicated by the dotted line positions in Fig. 3, just before pin I60reaches the upper end of the inclined surface I60, the pin I22 seats inthe socket I12. Further relative movement between the ram I30 and thearms I00 and I02 thus takes place about the fixed center afforded by thepin I22 and the permanent socket I12.

It will be appreciated that the lifting movement of the ram and pumpunit as influenced by the rocking movements of the handle 30 transfershydraulic fluid, such as oil, from a reservoir (not shown but contained,for example, within the ram cylinder) to the space behind the rampiston, the power and speed pumps affording a quick lift until the loadis engaged and a powerful but slower lift thereafter. When it isdesired. to lower the load, the control I56 may be operated to enable aretransfer of the liquid from the space behind the piston to thereservoir, at a desired regulated rate, underthe influence of the returnbias afforded by the load and by the spring. I80.

It will be noticed that the very low over-all height of theabove-described jack structure m= volves the use of relatively smallwheels. In connection with the above, as well as other small wheeledstructures, which areintended for use on irregular fioor surfaces, thearrangement of Fig. 6 is very advantageous. In this figure, a liftingcap 24 is associated with a frame structure 20, which may and preferablydoes duplicate the previously described frame structure 20 with theexception that the hoods, such as 46, which house the front wheels atthe respectively opposite sides of the frame, .are elongated so as toaccommodate a pair of front wheels 22 at each side of the frame. Bothpairs of wheels are in advance of the axis of the load, and the centerdistance spacing between the Wheels of each pair is preferablyproportioned to be somewhat in excess of the width of the normalirregularities in the associated floor I. One such irregularity isindicated at z. Accordingly, in moving the jack structure along thefioor, during the time that the foremost front wheels 22 are passingover the irregularity, the rearmost wheels 22 are still engaged with thenormal floor surface and support the jack structure. By the time therearmost' wheels 22 encounter the leading edge of the irregularity, onthe other hand, the foremost wheels 22 have passed thereover and havebecome effective to support the jack structure. The jack is,consequently, enabled to pass over the irregularity without bumping. Itwill be appreciated that the double wheel arrangement may, if desired,be used in connection with the rear end of the jack, although in manycases this is not found necessary in view of the fact that the frontwheels carry the major portion of the load.

Linkages embodying the arrangement described above with reference to thelifting arm 26 and the radius arms I00 and I02 may also be used toconsiderable advantage in instances where the initial lift afiorded bythe inclined planes is not needed. An illustrative such arrangement inconnection with an industrial truck structure is shown in Figs. '7 and8. In these figures, a frame structure 200 supported by suitable pairsof front and rear wheels 202 and 204 also supports a movable platform206. The frame 200 and platform 206 may partake of various differentconstructions, but are illustrated herein as being, respectively, ofupwardly presenting and downwardly presenting boxlike forms.

The platform and frame are connected together by similar pairs oflinkages arranged adjacent the front and rear ends of the platform, theindividual linkages of each pair also being similar. More particularly,each linkage comprises a lifting arm 2I0,'which is pivotally connectedto the platform at its upper end by means of a pin 2 l2, and which isprovided at its lower end with a roller 2I4, which rides in a slot 2 I 6provided in the side wall of the frame-200. Each linkage also comprisesa radius arm 2 I 8, which is pivotally connected at its lower end to theframe 200 by means of a pin 220 and which is pivotally connected to thecorresponding lifting arm 2 I0 by means of a pin 222. Each pin 222-isconnected to the corresponding pin of the immediately opposite linkageby means ofa cross-head 22d, and two cross-heads 222 are in turninterconnected by a push rod 226, having a connection 223 to anysuitable source of power. In the illustrated structure, the powerapplying member 228 extends to the left of the cooperating linkages and,consequently, a pulling force is required to be applied thereto in orderto rock the radius arms 2I8 in a counterclockwise or lifting direction.As in the previous instance, such coun-

